My HP printer is online, but documents aren't printing. Is there a print queue issue?

It's possible. Open the print queue (usually by double-clicking the printer icon in the system tray or going to Control Panel > Devices and Printers > right-clicking your printer > 'See what's printing'). Cancel all pending jobs in the queue. Restarting the print spooler service can also help (search for 'services.msc', find 'Print Spooler', right-click, and select 'Restart').